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Flexibility and hybrid are the (distant) future. Part 6 of alternatives to marine fuels.

November 5, 2019

Flexibility and hybrids are the (distant) future - however, with two months to go, less than 10% of ships have been modified to comply with the new directive.

In part 6 of the series on alternatives to marine fuels, we look at what the most obvious solutions will be in the future. In order to sail cleaner, it is currently only possible for ocean-going vessels to either use cleaner diesel or continue to sail on heavy diesel and run the exhaust gases through a scrubber. LNG is becoming a good alternative: technically feasible and scalable. Other alternative fuels are all still in the development phase, but one does foresee a bright future for these fuels. Technologically there are various possibilities, but why choose when a combination of new technology and (alternative) fuel offers more certainty.


An excellent alternative is a hybrid drive: partly electric and partly mechanical. This makes use of both the advantages of electric sailing at low power and the advantages of mechanical sailing at high power.

One of the disadvantages of an electric drive is that there is always a delaying factor when starting the engines. With a hybrid drive, the desired power is immediately available via the mechanical component: quick response and instant power.

Also in terms of maintenance, a hybrid scores better than the standalone mechanical or electric drives. Because of the lower number of operating hours of the motors, less mechanical maintenance is required. That means less downtime per year and therefore not only lower costs but also higher availability. And an electric drive system sec requires a heavy-duty installation. The electrical installation of a hybrid system, which is only used at low powers, is 10 times lighter and requires fewer components. This also has a positive impact on maintenance.

In the tugboat sector, hybrid propulsion seems to be becoming the norm. For the combination of waiting at low power and providing service at full power, a hybrid installation is the ideal drive.

Hybrid ships are also a good solution for ferry services, and possibly a first step towards all-electric shipping. Stena Line is experimenting with electric ships: batteries with a total capacity of 1 megawatt hour have been installed on the Stena Jutlandica, which sails between Gothenburg and Frederikshavn. The vessel can then switch to battery power when manoeuvring during port calls. An extended battery capacity of approximately 20 megawatt hours will then be connected to the propellers. This will make it possible to sail about 10 nautical miles on electricity. In a next step this will be increased to 50 nautical miles with a battery capacity of 50 megawatt hours. The batteries are charged when the ship is connected to shore power, which is an important focus for clean energy. However, the batteries can also be charged when the ship's generators are in use.

Oil tankers versus dry bulk ships; the same thing? 1

LNG as a (provisional) alternative

Sea-going vessels cruise the seas most of their time, while manoeuvring only takes a small part of the action. For these ships, a hybrid drive is not (yet) an alternative. But less than 10% of the ships are equipped with a scrubber and alternative fuels do not yet have a large share of the fuels. In the near future, most ships will therefore initially switch to MGO or ULSFO. The problem, as already outlined, is the production and supply of this fuel, and therefore the high costs involved.

Given the cost and initial scarcity of low-sulphur fuel, the question is whether shipowners and ship managers will comply with these IMO regulations? An IMO member state cannot opt out of the IMO guidelines, but each IMO member state can determine the penalties for non-compliance with the guidelines.

In light of these provisions, Indonesia announced in July that it will not require ships flying the Indonesian flag in national waters to comply with the sulphur rule: the cost of implementation is too high for shipowners. Only when the supply of MGO or ULSFO within Indonesia is functioning properly will the directive be complied with by Indonesian ships. Meanwhile, foreign ships operating in Indonesian waters do have to comply with the IMO directive. And of course, so do Indonesian ships on international routes.

But at the end of August, the Indonesian Transport Minister withdrew this ruling. State oil company Pertamina will produce 380 million liters of fuel with a maximum sulfur content of 0.5% per year. From the beginning of next year, the company will set up sales outlets for the low-sulphur fuel in Jakarta harbor and from a floating storage facility off Balikpapan in East Kalimantan province.

For new ships in particular, LNG is a good alternative, given the technical possibilities and the existing and planned infrastructure. But this too is an interim solution, as LNG still has substantial CO2 emissions.

What will be the future?

There is no crystal ball to predict which fuel or technology will become mainstream in the further future, up to 2050. Economic and geopolitical developments, future energy policy and technological developments are some of the uncertain factors that will influence this. Sea-going vessels sail worldwide and need a fuel that is available worldwide. In order to respond to the uncertainties of the future and also to meet the environmental requirements, the installation of engines that can be adapted relatively easily to environmentally friendly fuels is the most opportune. It therefore seems obvious to opt for dual-fuel, as the flexibility that these engines bring reduces the risks. Current fuel use is more flexible and with (minor) modifications the engines are suitable for future fuels. Ships in the short sea segment are usually smaller than the deep sea ships. The way in which these ships are used also differs considerably from the way in which deep-sea ships are used. Whereas deep-sea ships travel steadily for long periods at sea, shortsea ships travel shorter distances and their power requirements are variable. This makes it attractive for these vessels to operate with a hybrid propulsion system or electrically. DNV-GL has performed research into the energy mix in 2050. LNG will be the most important fuel, with over 40%. HFO with scrubbers will account for 10%, while LFSO and MGO will together account for 9%. Remarkably, ammonia takes up a quarter of the mix. The remaining 15% is taken up by other fuels, such as biofuels and hydrogen.

Flexibility and hybrids are the (distant) future - however, with two months to go, less than 10% of ships have been retrofitted to comply with the new directive. Part 6 of the series on alternatives to marine fuels.
Source: DNV-GL

For deep-sea vessels, dual-fuel propulsion seems to be the most future-proof investment, with the flexibility that these systems bring offering the possibility of switching to potential fuels of the future.

Hybrid propulsion seems to be the future for the shortsea sector. The efficient hybrid systems give lower consumption and associated lower costs, longer range, higher reliability, lower maintenance costs, lower emissions and easy operation.


And what is the current state of affairs?

The EGSCA (Exhaust Gas Cleaning Systems Association) expects at least 4000 ships to be equipped with scrubbers by 2020, which is about 7% of the total number of ships to comply with the new directive. In 2020, 150 ships will be powered by LNG, and another 150 or so will be on order; this represents around 0.5% of the total number. Finally, 300 ships (sailing and on order) are registered with the Maritime Battery Forum, also about 0.5% of the total. This means that only 10% of the total number of ships that have to comply with the directive are actually equipped for this purpose, 90% of the ships continue to operate as before. For the foreseeable future the alternative fuels will be MGO or ULSFO - without measures, these are the fuels which will be used.